The body of Chilean poet Pablo Neruda was unearthed from his tomb in Isla Negra, Chile, this week. The exhumation marks the beginning of a forensic analysis aimed at clarifying whether the Nobel prizewinner’s death in 1973 was from prostate cancer — as has been believed — or from poisoning, as a key witness has claimed.

Why has Neruda’s body been exhumed now, 40 years after his death?
Chilean judge Mario Carroza ordered the exhumation in February as part of an investigation that was opened in 2011 after Neruda’s former driver Manuel Araya said that the real cause of the poet’s death was an unscheduled injection that he received a few hours before dying on 23 September 1973. Neruda's death occurred just 12 days after the coup d’état that brought Augusto Pinochet to power to establish a right-wing dictatorship in the country. Neruda had served as ambassador to France under the deposed socialist president, Salvador Allende, and, like other Allende supporters, would have been persecuted by the new regime. On the basis of Araya’s testimony, the Communist Party of Chile, to which Neruda belonged, filed a criminal lawsuit in 2011.

Is it possible to trace the cause of the death after so many years?
“Beyond the time elapsed, the main problem is that we don’t have medical records on the poet’s illness,” says Patricio Bustos Streeter, director of Chile’s Legal Medical Service (SML) and coordinator of the forensic team. Records would provide details on what drugs Neruda was taking, helping to distinguish traces of them from those of possible poisons. “But we have the advantage that several techniques to mask toxics in the body did not exist four decades ago,” he says.

Unless they find other tissues, experts may have to rely on bones to gauge the extent of the cancer. “The presence of bone metastasis of the prostate cancer would confirm an advanced state of the illness. On the other hand, traces of toxics could be found in the spongy part of the bone that contained the bone marrow,” says Bustos.

Can the analysis reach a definitive conclusion?
False negatives are possible, says Barry Logan, president of the American Academy of Forensic Sciences, who is not involved in the investigation. “If experts find toxics that should not be there, then the result will be unequivocal,” he says. But some plant poisons are not detectable even in optimal forensic conditions, and traces of cyanide may be artifacts of decomposition, Logan says. “Finally,” he says, “the analysis may say whether a substance is present or not, but quantitative estimations are difficult in these conditions.” A poisoning that consisted of an overdose of a legal medication, such as morphine, would be difficult to detect.

Who is carrying out the analysis?
The forensic team is composed of Bustos and four other SML members, four experts from the University of Chile, four others from Spain and the United States and three observers from the International Committee of the Red Cross and the Argentine Forensic Anthropology Team — with a range of expertise, including medicine, anthropology, archaeology, pharmaceutical chemistry, photography and toxicology.

When and where will the analysis be done?
The SML and the University of Chile are in charge of cataloguing and conducting X-ray scans of the remains. Toxicological analyses will probably be carried out in Spain and the United States, “but we have received offers from Sweden, Switzerland and Canada”, Bustos says. The team is drafting a schedule for their analyses to submit to the judge for approval, but Bustos does not expect the results of the analyses for some months.

How likely is it that Neruda was poisoned?
Neruda’s nephew and biographer Bernardo Reyes told CNN Chile that the dictatorship did not begin poisoning its opponents until some time after his uncle’s death. “Poison was used in specific cases starting from the 1980s,” Bustos says. “But we don’t have a preconceived opinion: we are executing a judicial order and we will base our conclusions on evidence.”

This article is reproduced with permission from the magazine Nature. The article was first published on April 10, 2013.